Hub

The one device that never sleeps

The hub listens to the sensors by radio all the time, remembers what each one last said, and answers over Ethernet. It is what lets the sensors themselves stay asleep.

mizelum-hub

CAFE0001

LinkRadio

Supply3.29V

Ethernet100Mb/s

Devices heard02/32

Talks byRF24

Example readings

Hardware

Board: MuseLab nanoCH32V203
Processor: CH32V203C8T6, RISC-V, 64 KB flash, 20 KB RAM
Radio: nRF24L01+ module, 2.4 GHz, on its own SPI bus
Network: W5500 Ethernet module, 10/100 Mb/s
Power: 5 V over USB
Programming: Over its own USB port, no programmer needed

What it does

Hears: Up to 32 devices on one radio address
Keeps: The latest report of each, in memory
Serves: Lines of text over TCP, port 7737
Counts: Frames received and reports missed, per device
Reports: Its own supply voltage and Ethernet speed
Stage: Prototype

Prototype means: the firmware builds and has been flashed onto the board. Whether it then hears a sensor has not been seen yet.

Its protocol

Ask it by hand

Three commands, answered in plain text. Anything that can open a TCP connection can read a hub; Mizelum is only the most comfortable way.

Terminal

port 7737

$ nc 192.168.1.50 7737
PING
PONG
INFO
INFO name=mizelum-hub fw=0.3 proto=0 id=CAFE0001 uptime_ms=123456 nodes=2 radio=1 vdd_mv=3287 eth_mbps=100 eth_full=1 comm=rf24
LIST
NODE id=1A2B3C4D type=0001 fw=0.1 power=0 interval=10 seq=12 age_ms=5321 rx=40 lost=2 data=41E40C8407000000
END

The data of a device is its last report, as sent: here a supply of 3.300 V (41 E4 0C) and a counter at 7 (84 07 00 00 00).

Links

How a hub can talk to its sensors

A hub says which links it has. Today there is one. The other names are set aside for hubs that do not exist yet.

rf242.4 GHz radio (nRF24L01)Exists
loraLoRa long-range radioName only
lifiLi-Fi, data carried by lightName only
i2cI2C busName only
spiSPI busName only
canCAN busName only
rs232RS-232 serialName only
rs485RS-485 serialName only

Limits

What the hub does not do yet

Today

Its network address is fixed when its firmware is built; it cannot be found or use DHCP.
It serves one program at a time, so each one connects, asks and hangs up.
It forgets everything when restarted; sensors reappear as they report.

Not designed yet

Encryption: anyone with the same radio can read a frame or fake a sensor.
Pairing: two installations in range of each other see each other's sensors.
Commands from the hub to a sensor.